Sir Martin Sorrell has now departed his position from WPP ©Twitter

Sir Martin Sorrell, the keynote speaker at the 2015 International Olympic Committee (IOC) Session in Kuala Lumpur, has stepped down from advertising giants WPP amid an internal investigation into claims of personal misconduct. 

His departure after 33 years has been shrouded in secrecy, but is being considered as a "retirement".

The 73-year-old denied wrongdoing amid a now-completed investigation into the alleged misuse of WPP money but said it was in the "best interests of the business" to resign.

The Briton had been the best paid and longest-serving head of a FTSE 100 company having survived a shareholder revolt in 2015 over a £70 million ($100 million/€81 million) pay package.

WPP chairman Roberto Quarta will become executive chairman and work with two co-chief operating officers until the appointment of a new chief executive.

Sir Martin was given a rock-star reception by IOC members when he spoke in Kuala Lumpur with the message that the need to engage with young people has "never been more urgent".

IOC members queued up to take pictures with him afterwards in scenes considered virtually unprecedented.

In a virtuoso keynote speech, Sir Martin complimented his audience on the "very bold step" of setting up an Olympic TV Channel, while urging them to be "brave", "determined" and "proud of delivering the future of the Olympic Movement through this new medium".

He also urged IOC members to look on video games "as being a competitor".

Sir Martin then spoke to another packed room at the 2016 SportAccord Convention in Lausanne in which he warned the sports world to "adapt or die" following a mass of recent scandals.

It came on a day when a white paper was released introducing a new "Game Changer" methodology to reform sports governing bodies. 

Titled Implementing Good Governance Principles in Sports Organisations, the white paper was conducted by two companies owned by WPP; Burson-Marsteller and TSE Consulting.

Pedro Pablo Kuczynski, the keynote speaker at the 2017 IOC Session in Lima, has also since stepped down as President of Peru, shortly before Congress impeachment proceedings, amid a corruption investigation.

No keynote speech was given at February's IOC Session in Pyeongchang. 

"The current disruption is simply putting too much unnecessary pressure on the business, our over 200,000 people and their 500,000 or so dependents, and the clients we serve in 112 countries," Sir Martin said in a statement.

"That is why I have decided that in your interest, in the interest of our clients, in the interest of all share owners, both big and small, and in the interest of all our other stakeholders, it is best for me to step aside."

WPP shares have fallen 32 per cent in the last 12 months as competition from the likes of Google and Facebook has increased.

There has been a further 5.5 per cent fall since Sir Martin's departure and some analysts believe WPP, which comprises around 400 separate businesses, could be broken up.